1. Technical Field
One or more embodiments of the present invention relate to a loop gain adjusting circuit for a servo control in which a position of a member to be driven is detected, and the member to be driven is driven by an actuator such that the member to be driven is positioned at a target position.
2. Background Art
In control of various devices, a servo control is employed. In particular, in position control of a member, a servo control is widely in use which applies feedback control so that a detected position coincides with a target position.
In order to suitably execute such a servo control, loop gain in a feedback loop must be at a suitable value. Therefore, the loop gain must be adjusted. For the loop gain adjustment, a process has been applied in which, for example, a sine wave is added to a signal transmission path of the loop, the feedback loop is activated by the sine wave, and the loop gain is adjusted such that signals before and after the addition of the sine wave are identical. In other words, the signals before and after the addition are extracted, amplitudes of these signals are detected, and the loop gain is adjusted so that the amplitudes are equal to each other.
During the time when the signal goes through one loop, there may be cases where signal distortion occurs. In such a case, it is difficult to accurately measure the amplitude. In order to improve the precision of the amplitude measurement, for example, it may be necessary to calculate an average of measurement results of several periods.